The other morning I walked down the stairs carrying my four-year-old daughter and caught sight of us both in the hallway mirror. There she was, in all her youthful, flawless vitality, and there was I, the faded contrast. I admit it, I winced. You see, I used to think I looked pretty, and effortlessly, good for my age. Then, at 38, I had a baby, and then another at 41.

Now when my daughter slips her plump little hand into mine I see the vivid contrast between her velvet paw and my desiccated claw. Grey hairs sprout with the vigour of Japanese knotweed, I am inexorably spreading at the waist and cross little lines etch themselves between my unruly, fading eyebrows.

According to Kypros Nicolaides, Professor of Foetal Medicine at King’s College Hospital, older mothers have become an “epidemic”. Evidence released earlier this week from the Royal College of Obstetricians and Gynaecologists warns of the difficulties women over the age of 35 face trying to become pregnant, and that those who do manage it are at a higher risk of complications. Despite this, Western women are, for many reasons, waiting longer to start their families. “In 1970, 5 per cent of pregnant women were over 35, but in most European countries the figure is now 20 to 25 per cent,” Nicolaides says.

But for many of us, delighted at having children later in life, there is the secret horror at the thought of looking like your child’s grandparent. For many of today’s older mothers, being accused of being a granny has taken over from false accusation of pregnancy as the number one insult. Certainly, nobody told me that the ageing process accelerates like Lewis Hamilton once you hit 40. Have a baby and it progresses at warp speed; leftover baby fat simply morphs seamlessly into middle-aged spread. Lack of sleep and long hours pushing swings in winter gales can have a frightening effect on those of us without youth on our side. I’ve run around the park with a nice encouraging trainer, eaten only meat and oranges on the instructions of a Harley Street GP and twice a year I lie on a couch as Dr Michael Prager pincushions away my frown lines with Botox. “Most of my clients are between 35 and 50. Most are mothers,” he tells me.

Part of the problem is not only the coincidence of becoming a mother as I hit middle age but also that like many women of my generation I had the template of a genuinely young mother. When I was my daughter’s age my mother was only 27. By the time she was my age I’d left university. For my mother there were no grey hairs to worry about. She could even wear a halterneck dress without fear. Hell, she could run in it without fear. I felt very proud of my glamorous mum, and sometimes worry that my children might be embarrassed by their rather more elderly version.

Motherhood also brings the sudden realisation that not everyone is exactly the same age as you. From university onwards you tend to mix with a group of people who tend to be roughly your peers. But head out to baby groups and the nursery school gates and you find yourself hobnobbing with smooth-skinned, lion-haired women in their twenties and early thirties. Hire a nanny and she might be twenty years younger than you. A friend in her early forties started dying her hair the very day that she was mistaken for her son’s grandmother at toddler group.

Sometimes I am tempted to defy the yummy-mummy propaganda and give it all up, to let those grey roots push through and learn to love my lines. And perhaps if my kids were grown up I might feel confident enough to do that. I am lucky in that while I live in a part of London where a trip to the corner shop might be enlivened by a drive-by shooting, it is also a place where, certainly at my child’s school, the young mothers are almost outnumbered by the crones. It is not unusual to see mid-forties mums picking up from nursery, and when I left the hospital after having my second child the midwives said cheerily, “See you again”. My Botox-brigade peers and I are not old in the sense that our grandparents were old at our age. We defy the stereotypes about how to dress and behave, as well as when to have our children. We are confident in our abilities at work and as mothers, and all the studies show that older mothers raise happy, healthy, successful children.

So why can’t we simply be more comfortable with our age? I sometimes see a lovely, lithe woman with a mane of defiantly grey hair pushing a pram and think she looks fantastic. But I know I won’t be joining her. Even my own mother colours her hair, and to my children grey means old. I worry that if they realised how old I am they might be embarrassed, or worried about my longevity. So far they seem oblivious to the fact that mothers come in different vintages, and perhaps because I’m silly and vain, perhaps because I’m insecure, perhaps because I simply don’t feel old enough to be old, I intend to keep it that way for as long as I can. Or at least until the kids leave primary school.

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